Abstract：
The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies. In this study, we evaluated the removal of a gaseous mixture containing toluene, m-xylene, ethylbenzene, cyclohexane, butane, pentane, hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions. For the real-time measurement of hydrocarbons, a novel systematic approach was implemented using Selected-Ion Flow Tube Mass Spectrometry (SIFT-MS). The effect of the carbon source (∼9.5 ppmv) on (i) the bioreactors\' performance (BR1: dosed with only cyclohexane as a single hydrocarbon versus BR2: dosed with a mixture of the 8 hydrocarbons) and (ii) the evolution of microbial communities over time were investigated. The results showed that cyclohexane reached a maximum removal efficiency (RE) of 53% ± 4% in BR1. In BR2, almost complete removal of toluene, m-xylene and ethylbenzene, being the most water-soluble and easy-to-degrade carbon sources, was observed. REs below 32% were obtained for the remaining compounds. By exposing the microbial consortium to only the five most recalcitrant hydrocarbons, REs between 45% ± 5% and 98% ± 1% were reached. In addition, we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed. The abundance of species belonging to the genus Rhodococcus was below 10% in all bioreactors at the end of the experiments. This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors, along with a systematic approach for the development of SIFT-MS methods.
摘要：
微生物烃类去除的研究对未来生物修复策略的制定具有重要意义。在这项研究中,我们评估了含有甲苯的气态混合物的去除，间二甲苯,乙苯,环己烷,丁烷,戊烷,在充气搅拌生物反应器中的己烷和庚烷用红球红球菌接种并在非无菌条件下操作。为了实时测量碳氢化合物，使用选择离子流管质谱（SIFT-MS）实现了一种新颖的系统方法。碳源（~9.5ppmv）对（i）生物反应器性能的影响（BR1：仅使用环己烷作为单一碳氢化合物与BR2：使用8种碳氢化合物的混合物）和（ii）微生物群落随时间的演变进行了研究。结果表明，环己烷在BR1中的最大去除效率（RE）为53％±4％。在BR2中，甲苯几乎完全脱除，间二甲苯和乙苯，是最水溶性和最容易降解的碳源，被观察到。对于剩余的化合物,获得低于32%的RE。通过将微生物联盟仅暴露于五种最顽固的碳氢化合物中，达到45%±5%和98%±1%之间的RE。此外,我们观察到空气中的微生物填充生物反应器，碳源的类型影响微生物群落的发展。在实验结束时,在所有生物反应器中,属于红球菌属的物种的丰度低于10%。这项工作提供了基本的见解，以了解生物反应器中气态烃混合物的复杂行为，以及开发SIFT-MS方法的系统方法。
